Danfoss ECL Comfort 210 Operating Manual page 82

Operating Guide ECL Comfort 210/296/310, application A237/A337
MENU > Settings > Control parameters
Nz (neutral zone)
When the actual flow / duct temperature is within the neutral zone, the
controller does not activate the motorized control valve.
See Appendix "Parameter ID overview"
Set the acceptable flow /duct temperature deviation.
Set the neutral zone to a high value if you can accept a high
variation in flow temperature.
MENU > Settings > Control parameters
Min. act. time (min. activation time gear motor)
The min. pulse period of 20 ms (milliseconds ) for activation of the gear
motor.
See Appendix "Parameter ID overview"
If you want to tune the PI regulation precisely, you can use the following method:
• Set the 'Tn' (integration time constant) to its max. value (999 sec.).
• Decrease the value for the 'Xp' (proportional band) until the system starts hunting (i.e. gets unstable) with a constant amplitude (it
might be necessary to force the system by setting an extreme low value).
• Find the critical time period on the temperature recorder or use a stop watch.
This critical time period will be characteristic for the system, and you can evaluate the settings from this critical period.
'Tn' = 0.85 x critical time period
'Xp' = 2.2 x proportional band value in the critical time period
If the regulation seems to be too slow, you can decrease the proportional band value by 10%. Make sure there is a consumption
when you set the parameters.
82 | © Danfoss | 2017.05
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Temp. Critical time period
The neutral zone is symmetrical around the desired flow / duct
temperature value, i.e. half the value is above and half the value is
below this temperature.
Setting example
2
10
50
The setting should be kept as high as acceptable to increase the
lifetime of the actuator (gear motor).
Value x 20 ms
40 ms
200 ms
1000 ms
Time
VI.LG.R3.02